Canada



March 30,1926. 1,579,197

' J. W. DUNHAM PROTRACTOR ATTACHMENT FOR SQUARES Filed April 29, 1925 Patented Mar. 30, 1926.

a-I- a HQE.

JAMES WESLEY DUNHAM, OF BURNABY, BRITISH COLUMBIA, CANADA.

PROTRACTOR ATTACHMENT FOR SQUARES.

Application filed April 29, 1925.

To all to item it may concern:

Be it known that JAMES l VnsLnrDUN- HAM, a subject of the King of Great Britain, residing at Burnaby, British Columbia,

Dominion of Canada, has invented certain new and useful Improvements in Protractor Attachments for Squares, of which the following is a. specification.

This invention is an attachment for mechanics squares, such as try-squares, and the object is to provide a simple, practical and etficient attachment which may be easily mounted upon a try-square, and which will. afford a ready means for laying down angles upon the work.

In the drawing Figure 1 is a top plan view showing the attachment as mounted upon a try-square, and with the protractor attachment set as for an angle of 45 degrees;

Figure 2 is a bottom plan View;

Figure 3 is a detail of the protractor attaehment blank.

The invention consists of a rectangular sheet metal body portion or plate 1 having a flange 2 turned perpendicularly along one edge, the said flange being medially slotted as shown at 3 in a longitudinal direction. The element so formed is now adapted to set upon the stock 4: 0t thetry-squa-re 5, with the slot 3 engaging the blade 6 of the trysquare, and the flange 2 engaging the inner edge 11 of the stock l, that is to say, the edge of the stock from which the blade 6 extends. A relatively short, arouate slot 7 is cut adjacent the inner corner 8 of the portion 1, that is to say, adjacent the outer end of the slot 3 and concentrically with that corner 8, and a set screw 9 is passed 4Q down through the slot 7 and seated in the stock 4. The body portion 1 is thus piv otally secured to the stock l in such manner that the slotted end 10 of the flange 2 bears upon the said inner edge 11 of the stock 4 and serves as a pivotal bearing upon which the body port-ion 1 may be swung away from or towards the stock 1, in the laying out of angles on the work, while the slot 7 moves over the set screw 9. An integral,

curved finger 12 extends from the body portion 1 at the point relatively nearer to the Serial No. 26,780.

opposite end of the body portion, and reaches outwardly and b-ackwardly in a curve that is concentric with the slot 7 and the corner 8.

A relatively long slot 13 is cut in this fingel 12 concentrically with the slot 7; and a threaded stem 1& is set through this slot 13 and is anchored in the outer end of the stock 4:. A thumb nut 15 is mounted on the extended end of the stem l l. By this means, the body portion 1 may be locked rigidly at any desired angle relative to the stock a. A calibrated angle scale 16 is out along one edge of the slot 13. This attachment may be readily mounted upon any try-square and affords a handy means for laying out angles upon any work.

lVhile I have herein described a certain specific manner and method of constructing and assembling the elements of my invention, it is understood that I may vary from the same in minor details, not departing from the spirit of my invention, so as best to construct a practical device for the purpose intended, as defined in the appended claim.

I claim:

In combination with a try square, a protractor attchment therefor, comprising a rectangular plate having a flange turned,

perpendicularly along one edge, the said flange being longitudinally slotted at one end for engaging the blade of the square, while the flange itself is adapted to engage that edge of the stock of the square from which the blade of the square extends; the. said plate having a relatively short, arcuate slot cut in the said plate adjacent the slotted end of the said flange and concentric therewith; the said plate having an outwardly and backwardly directed arcuate finger pierced with a relatively long arcuate slot formed concentrically with the said short a-rcuate slot, and having a calibrated scale out along one edge thereof; a set screw passed through the short slot and anchored in the stock of the square; and a thumb screw locking element passed through the long slot and anchored in the said stock.

In testimony whereof I atfix my signature.

JAMES IVESLEY DUNHAM. 

